1. Field of the Invention
The present invention relates to a lens and a manufacturing method thereof, and more particularly to a lens and a light emitting device package formed by introducing surface mount technology (SMT).
2. Discussion of the Related Art
Along with the development of fields using light, parts using optical materials have been widely used in an optical communication device, an optical storage device, medical optical equipment and the like in various industrial fields. The parts using optical materials include a commonly-used lens, a prism, a beam splitter, a reflection mirror and a diffraction grating.
In the parts using optical materials, the lens is classified into a spherical lens, an aspherical lens, a ball lens, a GRIN lens and the like. Also, the lens is classified into an epoxy lens, a glass lens, a silicone lens and the like according to a material of the lens. Recently, a technology is being developed for a small-sized lens, a lightweight lens, a high-performance lens, and a lens having a large aperture. Particularly, along with the development of a light emitting diode (LED) industry, the demand and requirement for camera flash lenses of portable phones and lenses of LCD products using LED backlight sources are increasing.
Although the glass lens has high chemical and heat resistance, molding of the glass lens is complicated and expensive compared to molding of polymeric materials. Thus, a method of manufacturing glass by molding polymeric materials has been widely used.
Further, an injection molding method using a mold is widely used as a method of manufacturing a lens. In the injection molding method, a viscous fluid such as silicone gel or epoxy is injected into the mold and then molded, and the mold is separated, thereby manufacturing a lens. The lens manufactured by the above-mentioned method is installed at a specified position of a device having a light emitting device such as a light emitting diode or a laser diode. The lens refracts light emitted from the light emitting device to change a light path.
In a conventional method, cream solder having high electric and heat conductivity are formed at portions of light emitting devices of PCB by patterning cream solder only at desired positions using a mask. Electronic devices such as light emitting diodes and Zener diodes are arranged and positioned on the cream solder pattern. The cream solder is heated to a temperature higher than a melting point and cooled down and, thus, electric and optical devices and the metal pattern of PCB are electrically and mechanically connected. That is, after the electric and optical devices are connected, epoxy with high adhesivity is bonded to a portion for mounting a lens, and the lens is mounted on the portion with epoxy by a transfer device. Then, when heating to an appropriate temperature and cooling, the lens is bonded to PCB through epoxy.
However, the bonding process should use epoxy capable of bonding at a temperature less than the melting point of the cream solder. Accordingly, there is a limit in selecting the epoxy and cream solder. Since the electric and optical devices are connected and the lens is bonded, the processing time increases. Also, since the light emitting devices are connected to PCB and the lens is bonded after increasing the temperature, the PCB may become twisted. Thus, it is impossible to accurately arrange the light emitting devices and lens and the unit cost increases.